This thesis addresses the criticism of the philosophy of Immanuel Kant put forward by Quentin Meillassoux under the charge of ‘correlationism.’ It uses Meillassoux’s interpretation of Kant as a starting point to develop an alternative interpretation in which space plays a central role within Kant’s thought, thus contributing to the wider philosophy of space. The argument progresses through an analysis of the three stages of dogmatism, skepticism and Criticism, which are central to Kant’s thought and which Meillassoux attempts to circumvent. It demonstrates how Kant develops his Critical philosophy through a rejection of dogmatism as a commitment to the principle of sufficient reason, which is reconfigured using the insights of Hume’s skepticism. Thus the system outlined in the Critique of Pure Reason is at heart a temporal philosophy, in which the principle of sufficient reason is reconceptualized in terms of the issue of timedetermination. Meillassoux’s alternative system of ‘speculative materialism,’ it is argued, proceeds along the same path: Criticizing the principle of sufficient reason and reconfiguring it through the insights of Hume’s skeptical problematization of induction, in order to assert a temporal philosophy based upon the ‘hyper-chaos’ of the ‘principle of unreason.’ However, with this unexpected parallel between Kant and Meillassoux in regard to the issue of time, the problematic role of space also becomes apparent. Meillassoux’s temporal philosophy is disrupted by his use of the spatial metaphor to fully express the features of time that he sets out, and thus space becomes a point of tension within his temporal system of ‘speculative materialism.’ Working back through the parallel between Meillassoux and Kant reveals that the role of space and its connection to time is also a problematic point of tension within Kant’s Critical philosophy and one that is central to his reworking of the Critique of Pure Reason for the 1787 B-Edition. Thus, through a detailed interpretation of the Critical philosophy, and especially its role in the Refutation of Idealism added to the B-Edition, the centrality of space within Kant’s system is reasserted and evaluated. This recognition of the importance of space and its relation to time within Kant’s system also provides the means to reassess Meillassoux’s criticism of Kant as a ‘correlationist’ and recast the debate between idealism and realism in the history of post-Kantian philosophy terms of the roles and relations of time and space.